Eddy currents are induced when:

$A$ metal sheet is placed in a magnetic field that changes from zero to maximum. If the figure shows the direction of eddy currents,then the direction of the magnetic field is:

$A$ bar magnet is released from rest coaxially along the axis of a very long,vertical copper tube. After some time,the magnet:

$A$ sheet is placed on a horizontal surface in front of a strong magnetic pole. $A$ force is needed to:
$A$. hold the sheet there if it is magnetic.
$B$. hold the sheet there if it is non-magnetic.
$C$. move the sheet away from the pole with uniform velocity if it is conducting.
$D$. move the sheet away from the pole with uniform velocity if it is both,non-conducting and non-polar.
Choose the correct statement$(s)$ from the options given below:

When a small magnet is allowed to fall through an aluminium pipe,it falls with an acceleration less than $g$. Why?

In which of the following devices,the eddy current effect is not used?